<s>
ROUGE	B-General_Concept
,	O
or	O
Recall-Oriented	O
Understudy	O
for	O
Gisting	O
Evaluation	O
,	O
is	O
a	O
set	O
of	O
metrics	O
and	O
a	O
software	O
package	O
used	O
for	O
evaluating	O
automatic	B-Application
summarization	I-Application
and	O
machine	B-Application
translation	I-Application
software	O
in	O
natural	B-Language
language	I-Language
processing	I-Language
.	O
</s>
<s>
ROUGE-N	O
:	O
Overlap	O
of	O
n-grams	B-Language
between	O
the	O
system	O
and	O
reference	O
summaries	O
.	O
</s>
<s>
ROUGE-1	O
refers	O
to	O
the	O
overlap	O
of	O
unigrams	B-Language
(	O
each	O
word	O
)	O
between	O
the	O
system	O
and	O
reference	O
summaries	O
.	O
</s>
<s>
ROUGE-2	O
refers	O
to	O
the	O
overlap	O
of	O
bigrams	O
between	O
the	O
system	O
and	O
reference	O
summaries	O
.	O
</s>
<s>
ROUGE-L	O
:	O
Longest	O
Common	O
Subsequence	O
(	O
LCS	O
)	O
based	O
statistics	O
.	O
</s>
<s>
Longest	O
common	O
subsequence	O
problem	O
takes	O
into	O
account	O
sentence-level	O
structure	O
similarity	O
naturally	O
and	O
identifies	O
longest	O
co-occurring	O
in	O
sequence	O
n-grams	B-Language
automatically	O
.	O
</s>
<s>
ROUGE-W	O
:	O
Weighted	O
LCS-based	O
statistics	O
that	O
favors	O
consecutive	O
LCSes	O
.	O
</s>
<s>
ROUGE-S	O
:	O
Skip-bigram	O
based	O
co-occurrence	O
statistics	O
.	O
</s>
<s>
ROUGE-SU	O
:	O
Skip-bigram	O
plus	O
unigram-based	O
co-occurrence	O
statistics	O
.	O
</s>
